Firstly and most importantly you can not submit a sale unless your current location is determined. Therefore, the "Location Services" should be enabled, and the device should be connected to the Internet. You can tell when your location is determined if in the "Sumbit" tab the fields under the "Store Address" are filled.
Once your location is known, you can fill the other fields. It is not required to give the "Start" or the "End" date, but if you do wish to do so, you must give both dates.
You submit your sale by clicking on the "Submit" button in the top right corner. Please wait for a couple of seconds to receive the responce of acceptance from the server. If something went wrong, you will receive an error message.